The present invention relates to a transparent touch panel attached on an LCD or a similar flat display device, and electronic equipment using the transparent touch panel.
One type of structural design used for transparent touch panels (TTP) is known as the analog resistive-layer type. An analog resistive-layer TUP comprises a lower transparent resistive-layer substrate (1) made of a transparent resistive-layer made of Indium Tin Oxide (ITO) formed on a transparent glass plate or a similar material, the resistive-layer having a pair of belt-shape electrodes provided at both sides, and an upper transparent resistive-layer substrate (2) made of a transparent flexible insulating base material, such as a polyester film, the transparent resistive-layer having a pair of belt-shape electrodes formed on the lower surface in the same way as those of the lower transparent resistive-layer substrate. The above-described two substrates (1) and (2) are coupled together after shifting the relative orientation of the belt-shape electrodes by 90 degrees, with a spacer interposed between the respective resistive-layers. This completes a finished analog type TTP.
There have been a number of ways for separating and insulating the resistive-layer of substrate (1) from that of substrate (2) in regions other than the input area (operation area) of the analog resistive-layer TTPs. The separation methods include; (a) chemically etching the resistive-layer with an acid or alkaline solution, (b) affixing an insulating substrate patterned in a certain desired shape on the resistive-layer, and (c) coating the resistive layer with an epoxy resin, or similar thermosetting resin. Conventionally, any one of the above-described methods has been used for forming the insulating section.
These methods of forming the insulating section have following drawbacks.
The chemical etching method uses a strong acid or alkaline liquid, which is hazardous to the factory workers in the environment. Wastewater from the factory requires an appropriate environmental treatment, which adds additional cost.
The method of affixing a patterned insulating substrate requires that such an item be prepared in various shapes in accordance with various design concepts of TTPs. This leads to a complication in the manufacturing process, and hence to a higher manufacturing cost.
The method of coating the resistive layer a thermosetting resin is advantageous in that it can provide the insulating section in any desired form. It is a method that works for large scale production. However, the curing of resin requires heating; therefore, only a heat-resistive material can be used for the substrate of transparent resistive-layer. Furthermore, the thermosetting resin printed precisely to a certain specific form tends to become imprecise along the edge and in corners due to the lowered viscosity caused by the heat applied during curing.
The present invention addresses the above technical problems in the conventional methods of providing the insulating section, and offers a TTP in which the insulation on the resistive-layers is well secured in regions other than the input section and reveals a remarkable advantage for large scale manufacturing. Furthermore, the TTPs manufactured in accordance with the present invention generate very few environmental hazards. Also described in the present invention is an electronic system incorporating the TTP.
The present invention is a transparent touch panel comprising two substrates, each having a transparent resistive-layer, the substrates being coupled together with the respective resistive-layers facing each other while keeping a specific separation. The TTP functions as an electrical switch when one of the substrates is pressed. The TTP of the present invention includes an insulating section on one of the transparent resistive-layers for separating the transparent resistive-layers from each other in a region other than the input section by using a UV (ultra violet) curing resin or an EB (electron beam) curing resin, on at least one of the substrates having a transparent resistive-layer.
In a TTP of the present invention, it is easy to secure a sure insulation on the transparent resistive-layers in a region other than the input section. Since the resin used for forming the insulating section in the present invention is cured at a low temperature, the substrate can be made of a plastic material with low heat-withstanding capabilities. The insulating section may be formed in any desired shape, and it can be cured within a very short period of time; which is quite an advantage for carrying out large scale production. Since the curing is completed within a very short curing time, it offers still another advantage. Namely, the insulating section, even if it is has a fine pattern, can be formed precisely in a desired arrangement because the resin spreads only minimally during the curing time. Since formation of the insulating section does not use an acid, alkaline solution, or organic solvent that requires special treatment before disposal, a TTP of the present invention has the additional advantages of providing increased worker and environmental safety. The same applies to an electronic system employing the TTP.